Arsenic
On rare occasions, arsenic forms rhombohedral crystals. It commonly occurs as granular, botryoidal, or stalactitic masses. It is pale gray and tarnishes to dark gray. The streak is pale gray. Arsenic is an opaque mineral, and it has a metallic luster.
FORMATION Forms mainly in hydrothermal veins.
TESTS Heated, arsenic gives off fumes smelling of garlic.
Group: NATIVE ELEMENTS
Composition: As
Hardness: 3½
SG: 5.72–5.73
Cleavage: Perfect basal
Fracture: Uneven
